|Publication number||US7414491 B2|
|Application number||US 11/773,930|
|Publication date||Aug 19, 2008|
|Filing date||Jul 5, 2007|
|Priority date||Sep 28, 2004|
|Also published as||US20060066414, US20070257745, WO2006036672A1|
|Publication number||11773930, 773930, US 7414491 B2, US 7414491B2, US-B2-7414491, US7414491 B2, US7414491B2|
|Inventors||J. Aiden Higgins|
|Original Assignee||Teledyne Licensing, Llc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (10), Non-Patent Citations (7), Referenced by (5), Classifications (8), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This is a Continuation application claiming benefit of patent application Ser. No. 11/090,599, filed Mar. 24, 2005 now abandoned, and Provisional Application Ser. No. 60/614,243, filed Sep. 28, 2004.
1. Field of the Invention
This invention relates to electronic systems, and more particularly to the transmission of electromagnetic signals.
2. Description of the Related Art
An electromagnetic wave propagating through space has orthogonal electric (E) and magnetic (H) field components commonly described in Cartesian coordinates. The concept of using an electromagnetic beam for transmitting information is attractive at high frequencies, such as the frequency band of approximately 20-40 GHz. Transmission of the electromagnetic beam to a destination typically involves the use of a signal-guiding element and one or more amplifiers in a power amplifier module. Functions such as switching and bi-directional amplification are used to accomplish the system.
In U.S. Pat. No. 6,756,866, J. Higgins describes a signal-guiding element in the form of a waveguide that has high impedance structures on its walls to provide phase shifting while maintaining power density across its width for amplification. The surface impedance of the walls is voltage controlled using voltage dependent capacitance which determines the resonant frequency of the wall impedance structure and results in a change of the wave propagation constant and, subsequently, the phase of transmission coefficients (S21 and S12). J. Higgins suggests the use of the impedance structure on all four walls of the waveguide to support simultaneous and active phase control of two linearly and orthogonally polarized microwave or millimeter wave signals. An array amplifier is an array of small amplifiers each with an input antenna and an orthogonally oriented (with respect to the input antenna) output antenna. The amplified wave is polarized orthogonally with respect to the input wave. The combination of such a waveguide and an array amplifier can establish a directional power amplifier module for guiding and amplifying the input signal.
One problem associated with the prior art power modules described above is the unidirectionality of their associated amplifier arrays. Amplifier arrays use input and output antennas that are perpendicular to one another and, because antennas radiate in both upstream and downstream directions, require polarizers to set the direction of gainful propagation. The orientation of the antennas in comparison to the polarization of the return signal prevents bidirectional signal gain for rotationally fixed power modules. If bidirectional signal gain is required, a second power module is typically used. This results in duplicative power modules.
A method and structure are provided that can be used for bi-directional amplification without duplicative power modules, or for other applications that benefit from controllably varying the polarization of a signal such as an RF switch. A polarized input signal having orthogonal E-field components is propagated by a waveguide surface whose impedance is varied to shift the phase of one of the E field components independently from the other, thus changing the composite signal's polarity.
In one embodiment, at least two pairs of opposing impedance-wall structures guide the signal, with different voltages applied to the walls of their respective pair to vary the wall impedance and, thereby, the propagation constant.
A bi-directional amplifier system that uses the polarization-changing apparatus rotates the signal's polarization in one direction of propagation, but not a return signal sent in the opposite direction, to achieve bi-directionality.
These and other features and advantages of the invention will be apparent to those skilled in the art from the following detailed description of preferred embodiments, taken together with the accompanying drawings.
The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Like reference numerals designate corresponding parts throughout the different views.
The invention provides a method and system for changing the polarization of a high-frequency input signal. A linearly polarized signal having an E-field component is propagated a suitable transmission system in which one of the E-field's orthogonal vector components can be phase shifted with respect to the other to change the polarization of the signal. For example, one vector component can be phase shifted relative to the other to change the polarization of a polarized signal from linear to circular and then to linear at a 90 degree angle to the original polarization.
Several embodiments are described in the context of an impedance-wall waveguide used to match the polarization of an input E field to the input antenna of an amplifier array. Other applications also make use of the changeable polarization, including switching, phase shifting, and signal isolation.
The waveguide walls are operated in respective opposed pairs to guide a polarized input signal along the waveguide's longitudinal direction (z)0. Each wall has a high-impedance structure 110 to maintain a substantially uniform power density across the waveguide's width. A plurality of conductive strips 112 on each wall are arranged transverse to the input signal and facing the waveguide's interior to support the input signal's H field component through the waveguide 100. The conductive strips 112 are made of a conductive material, preferably gold, and are formed on a dielectric substrate 114 (such as, but not necessarily, Gallium Arsenide (GaAs)). Other suitable substrates include ceramic, plastic, polyvinyl carbonate (PVC) and high resistance semiconductor materials. A conductive exterior sheet 116 is electrically coupled to each conductive strip 112 by vias 118 extending through the substrate 114.
On the left and right walls 106, 108, vertical-vector control strips 120 alternate with the conductive strips 112 on the interior surface of the dielectric substrate 114, and are coupled to terminals V1LFT and V1RT, respectively, to receive a control voltage. In the embodiment of
The top and bottom walls 102, 104 have a similar strip-impedance structure 110, with conductive strips 112 alternating with horizontal vector control strips 126. The horizontal vector control strips 126 are coupled to voltage terminals V2TOP and V2BOT to vary the pre-existing gap capacitance between successive strips 126, 112. A variation in the voltage communicated to the horizontal-vector controls strips 126 from terminals V2TOP and V2BOT operates to vary the propagation constant of the horizontal vector component of the E field Ex, the gap capacitance and the resonant frequency of the top and bottom walls 102, 104 in a manner similar to the side walls.
In operation, terminals V1LFT/V1RT and V2TOP/V2BOT enable independent voltage control of the left/right and top/bottom wall structure pairs 106/108 and 102/104, respectively, for independent phase control of the vertical and horizontal vector components, Ey and Ex, respectively, of the input signal's Exy field component. When one vector component reaches 90 degrees out of phase with the other, the E field has changed from linear to circular polarization. As the relative phase difference between the two vector components approaches 180 degrees, the E field again becomes linearly polarized, but with an orientation that is 90 degrees rotated from the initial orientation.
Although the waveguide 100 is illustrated having a square cross-section, the waveguide may be constructed with wall structure pairs positioned in another polygonal cross-section such as a rectangle, hexagon or octagonal. Curved and opposing wall pairs may also be used.
In the waveguide described above, terminals V1LFT/V1RT and V2TOP/V2BOT preferably receive bias voltages between approximately 1 and 10 Volts. The various other elements of this particular waveguide have the following approximate thicknesses and widths:
Conductive strips 112
Insulating substrate 114
Conductive voltage strip 200
Via cap 202
Insulator strip 204
wide-band gap layer 208
N− anode layer 210
N− cathode layer 212
N+ ohmic contact layer 214
N+ diode connecting layer 218
In operation, a positive voltage applied to terminals V1LFT and V1RT is communicated to conductive voltage strip 200 to bias the varactors 206, 207. The bias results in a reduced total capacitance through a loop circuit ALOOP defined by the control strip 120, the varactors 206 and 207, the conductive strip 112, the exterior sheet 116 and back to the control strip 120. A reduced capacitance through the loop circuit ALOOP increases the resonant frequency of a current generated by an H field companion to the vertical vector component of the E field, resulting in increased resonant frequency and phase velocity (due to a reduced propagation constant β) for the vertical vector component of the E field. As the voltage at terminals V1LFT/V1RT is reduced, the capacitance across the varactors 206, 207 increases, resulting in the gap capacitance increasing, and the left and right walls 106, 108 resonate at a lower frequency to reduce the phase velocity of the vertical vector component. The top and bottom wall pair is controlled in the same manner with the voltage at terminals V2TOP/V2BOT to control the E field's horizontal vector component. With independent phase control of each vector component of the E field, the E field's polarization can be controlled by independently controlling the voltages at terminals V1LFT/V1RT and V2TOP/V2BOT.
Curve 300 in
The impedance-wall structure illustrated in
With impedance-wall structures on all four sides of the waveguide 100, the waveguide can be used to change the polarization of an input signal introduced to the waveguide with E field components in the x and y directions of
The above embodiments are shown applied to a bi-directional power amplifier in
Typically, a system outputting a signal oriented in one direction would receive a similarly oriented linearly polarized return signal in the reverse direction with an E field component ER for amplification. In the illustrated embodiment, ER passes through the −45° polarizer 510 and bias voltages are applied to the impedance-wall waveguide 100B so that it rotates the ER polarization by 90 degrees into alignment with the input antennas 504. ER is accordingly amplified by the amplifiers 506 and radiated by output antennas 508. Because the output antennas 508 are perpendicular to the input antennas, the polarization of amplified ER is rotated 90 degrees for propagation through the waveguide 100A. Waveguide 100A is also operated in an active mode, with bias voltages applied to its impedance walls to rotate the polarization of amplified ER by 90 degrees, allowing it to pass through the 45° polarizer 502. The directions “forward” and “reverse” are presented for convenience of discussion and may be interchanged. For example, an input signal initially presented to waveguide 100B for polarization rotation may be labeled as a forward input signal.
As illustrated in
While several illustrative embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Such variations and alternate embodiments are contemplated, and can be made without departing from the spirit and scope of the invention as defined in the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3721923 *||Aug 6, 1971||Mar 20, 1973||Rca Corp||Comprising a slab of semiconductor material|
|US4263570 *||Oct 24, 1978||Apr 21, 1981||The United States Of America As Represented By The Secretary Of The Navy||Optical phase shifter|
|US4266203||Feb 22, 1978||May 5, 1981||Thomson-Csf||Microwave polarization transformer|
|US4271534||Sep 17, 1979||Jun 2, 1981||Alps Electric Co., Ltd.||Microwave receiver|
|US4348773||Jan 15, 1980||Sep 7, 1982||Ignazio Caroli||Microwave receiver converters having a hybrid waveguide structure|
|US5032805 *||Oct 23, 1989||Jul 16, 1991||The United States Of America As Represented By The Secretary Of The Army||RF phase shifter|
|US5099214 *||Sep 27, 1989||Mar 24, 1992||General Electric Company||Optically activated waveguide type phase shifter and attenuator|
|US6603357||Sep 29, 1999||Aug 5, 2003||Innovative Technology Licensing, Llc||Plane wave rectangular waveguide high impedance wall structure and amplifier using such a structure|
|US6756866||Sep 29, 2000||Jun 29, 2004||Innovative Technology Licensing, Llc||Phase shifting waveguide with alterable impedance walls and module utilizing the waveguides for beam phase shifting and steering|
|US6919862 *||Sep 26, 2003||Jul 19, 2005||Rockwell Scientific Licensing, Llc||High impedance structures for multifrequency antennas and waveguides|
|1||Hao Xin, et al., "Electromagnetic Crystal (EMXT) Waveguide Band-Stop Filter", IEEE Microwave and Wireless Components Letters, vol. 13, No. 3, pp. 108-110 (Mar. 2003).|
|2||Higgins J.A. et al., "Ka-Band Waveguide Phase Shifter Using Tunable Electromagnetic Crystal Sidewalls", IEEE Transactions On Microwave Theory and Techniques, vol. 51, No. 4 (Apr. 2003).|
|3||Hollung, S. et al. "Bi-Directional Quasi-Optical Lens Amplifier", IEEE MTT-S, pp. 675-678 (Jun. 1997).|
|4||J.A. Higgins, et al., "Characteristics of Ka Band Waveguide using Electromagnetic Crystal Sidewalls", IEEE MTT-S Digest, pp. 1071-1074 (2002).|
|5||Michael P. DeLisio et al., "A Ka-Band Grid Amplifier Module with Over 10 Watts Output Power", IEEE MTT-S Digest, pp. 83-86, (2004).|
|6||U.S. Appl. No. 11/090,599, Non-Final Office Action, Notice of References Cited by the Examiner (PTO-892), Reference cited by Applicant (PTO-1449), mailed Sep. 19, 2006.|
|7||U.S. Appl. No. 11/090,599, Notice of Allowance, mailed Jul. 6, 2007,|
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|US8598960 *||Jan 29, 2009||Dec 3, 2013||The Boeing Company||Waveguide polarizers|
|US8816798||Feb 24, 2010||Aug 26, 2014||Wemtec, Inc.||Apparatus and method for electromagnetic mode suppression in microwave and millimeterwave packages|
|US9000869||Oct 19, 2011||Apr 7, 2015||Wemtec, Inc.||Apparatus and method for broadband electromagnetic mode suppression in microwave and millimeterwave packages|
|US20140055216 *||Aug 22, 2013||Feb 27, 2014||City University Of Hong Kong||Transmission line and methods for fabricating thereof|
|U.S. Classification||333/12, 333/157, 333/248, 333/21.00A|
|International Classification||H01P1/18, H01P1/165|
|Sep 24, 2008||AS||Assignment|
Owner name: ROCKWELL SCIENTIFIC LICENSING, LLC, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HIGGINS, J. AIDEN;REEL/FRAME:021581/0591
Effective date: 20050302
Owner name: TELEDYNE LICENSING, LLC, CALIFORNIA
Free format text: CHANGE OF NAME;ASSIGNOR:ROCKWELL SCIENTIFIC LICENSING, LLC;REEL/FRAME:021581/0786
Effective date: 20060918
|Feb 10, 2009||CC||Certificate of correction|
|Mar 10, 2009||CC||Certificate of correction|
|Feb 21, 2012||FPAY||Fee payment|
Year of fee payment: 4
|Mar 9, 2012||AS||Assignment|
Owner name: TELEDYNE SCIENTIFIC & IMAGING, LLC, CALIFORNIA
Effective date: 20111221
Free format text: MERGER;ASSIGNOR:TELEDYNE LICENSING, LLC;REEL/FRAME:027830/0206